A large number of people suffering from diabetes use some form of daily insulin therapy to maintain close control of their glucose levels. Currently, there are two principal modes of daily insulin therapy. The first mode includes syringes and insulin pens. These devices are simple to use and are relatively low in cost, but they require a needle stick at each injection, typically three to four times per day. The second mode includes infusion pump therapy, which entails the purchase of an insulin pump that lasts for about three years. The initial cost of the pump can be significant, but is superior from a user perspective. Consequently, the overwhelming majority of patients who have used pumps prefer to remain with pumps.
Infusion pumps, although more complex than syringes and pens, offer the advantages of continuous infusion of insulin, precision dosing and programmable delivery schedules. This results in closer blood glucose control and an improved feeling of wellness.
The use of an infusion pump requires the provision of a number of components including disposable components, such as an infusion set or pump set, which conveys the insulin from a reservoir within the pump into the skin of the user. An infusion set typically consists of a pump connector, a length of tubing, and a hub or base from which an infusion cannula or catheter extends. The hub or base has an adhesive that retains the base on the skin surface during use. Once applied, the infusion cannula or catheter can be inserted into the skin with the aid of a manual or automatic insertion device.
Another type of insulin pump is a patch pump. Unlike a conventional infusion pump and infusion set combination, a patch pump is an integrated device that combines most or all of the fluidic components, including the fluid reservoir, pumping mechanism and mechanism for automatically inserting the cannula, in a single housing which is adhesively attached to an infusion site on the patient's skin, and does not require the use of a separate infusion or tubing set. A patch pump containing insulin adheres to the skin and delivers the insulin over a period of time via an integrated subcutaneous cannula. Some patch pumps may wirelessly communicate with a separate controller device (as in one device sold by Insulet Corporation under the brand name OmniPod®), while others are completely self-contained. Such devices are replaced on a frequent basis, such as every three days, when the insulin reservoir is exhausted or complications may otherwise occur, such as restriction in the cannula or the infusion site.
There are many available types of infusion sets, including steel needle infusion sets and soft catheter sets. Steel needle infusion sets can be provided with a sharpened cannula which can be automatically or manually inserted into a patient and left in place with the set. Soft catheter sets are typically inserted into a patient with the aid of a manual or automatic insertion device using a steel introducer needle, which is removed from the patient after insertion to leave the soft catheter in place.
Infusion sets and patch pumps can be placed and manually or automatically activated to insert the cannula. In the case of manual activation, the insertion and retraction of the cannula can vary in response to the user force applied, and speed, smoothness and angle thereof. This variability can lead to an increased rate of insertion failure and/or discomfort to the user. Also, in each case, a large number of activation and retraction components may be required for the construction and use of the infusion set or patch pump. This leads to increased cost and a greater chance of failure or improper operation. Further, any requirement for a large number of components can result in a larger and heavier device, which is undesirable since it will add to the discomfort of the user.
Accordingly, a need exists for an infusion device that facilitates insertion of a cannula, and if required, retraction of the cannula, while reducing the number of components required for the construction and use of the infusion device.